Hoganite and paceite (along with calclacite) are currently the only known minerals containing the organic acetate ion (CH3CHO2)-
Minerals Containing the Acetate (Ethanoate) Ion
||Ca(CH3COO)Cl · 5H2O
||Cu(CH3COO)2 · H2O
||CaCu(CH3COO)4 · 6H2O
Although not new minerals of the three, hoganite has been in the news recently through a discovery of fabulous crystals in Morocco.
The story goes that in March 2017 Spanish dealer Nicolas Tesoros Naturales from Zaragoza acquired some peculiar copper samples from Bou Nahas Mine, Alnif, Tarhbalt, in the Meknès-Tafilalet Region during his annual trip to Morocco. Spanish collector Manuel Mesa was able to obatin a sample, and decided to send it for analysis by Joy Desor in Germany.
|Bou Nahas Mine, Alnif, Meknès-Tafilalet Region Morocco - courtesy Joan Rosell - Rosell Minerals
These samples were P-XRD, Raman and SEM-EDS analysed and the blue crystals have turned out to be hoganite, a very rare mineral, and in extraordinary good crystals.
The minerals hoganite and paceite were first discovered in Australia at the Potosi Mine at Broken Hill in New South Wales occurring as scant single crystals in a gossanous matrix, the "feeder" for the acetate is believed to be rotting vegetation or mine timbers.
Previously hoganite was only found, and this way at Potosi Mine and at two copper mining locations in the USA, Courland Mine in Arizona and Centennial Mine in Michigan.
Both hoganite and paceite are identical to synthetic compounds with the same formula and are relatively easy to synthesise.
More hoganite bearing specimens were also available at Munich Show in October 2017.
It is due to these reasons there have been some discussions over the paragenesis/veracity of the new Moroccan find. There is a very good thread on FMF that covers this subject - though nothing conclusive, the presence of malachite might tend to the "natural" side of the argument.
Again it is an example of the interesting and sometimes contraversial area of mineralogy; where environment/man/mining has triggered a mineral forming process either to create new minerals or existing mineral types with an anthprogenic setting.
Let us not forget the people honoured by naming of hoganite and paceite, here is a section from the ABC website written in February 2006 by jounalist Lisa Howard
Minerals to be named after their collectors
Two Broken Hill mineral collectors have won immortality by finding two new minerals which are now named after them. Frank Pace and Graham Hogan found the minerals in an open cut mine in Broken Hill. The two minerals, now known as Paceite and Hoganite, are acetates of copper and the first in their class. And after collecting minerals for 35 years Frank Pace reckons it's the ultimate honour. "We haven't even got a piece for ourselves, not just yet anyway - unless Graham comes across a piece in his shed when he cleans it out. It's a great honour." So how did it actually come about?
Well as Frank explains, it was a combined effort between himself, his mate Graham Hogan and a few Sydney scientists. "Graham's a keen collector and I'm a keen hoarder, so between us we found two new minerals."
According to Professor Williams, one of the scientists involved in 'describing the mineral' about 50-75 new minerals come to light each year. But modern mining practices don't seem to be as conducive to finding new minerals as was common in the open cut mines. "We were lucky in this particular case - Graham noticed some unusual specimens and then Frank drew them to our attention.”
The actual describing process took five scientists working on and off about 18 months. Professor Williams says it's unlikely there's large amounts of Hoganite and Paceite across the globe, but says the minerals help to tell part of the story of the earth's history. But, however small it is, as far as Frank Pace is concerned, it's a piece of Broken Hill and a dream come true.
Professor Pete Williams: Professor of Chemistry, University of Western Sydney
Frank Pace: Namesake of Paceite
|We will be continuing with the theme of Broken Hill collectors with Roger's next blog see link below.